130,375 research outputs found
Comunicazione, complessità, organizzazione e risultati di una ricerca sugli stili comunicazionali e relazionali nelle istituzioni sanitarie
No full textRouting and Wavelength Assignment OTDM/WDM Networks with Physical Impairments
No full textIn this paper we evaluate the impact that physical impairments have on the resource
consumption in Wavelength Division Multiplexing (WDM) networks where bandwidth
utilization is optimized performing an Optical Time Division Multiplexing (OTDM). In
particular we propose two modified heuristics to solve the problem of Routing and
Wavelength Assignment (RWA) in OTDM/WDM networks where physical impairments
are taken into account. In literature this RWA problem is referred to as S-RWA (Super-
Lightpath RWA) because Super-Lightpath must be routed. If D is the OTDM
multiplexing degree, a Super-Lightpath is able to carry all connections from a single
source node to D different destinations using the D time-slot carried out on each
wavelength. The effectiveness of the technique is evaluated on the COST 266 physical
topology and when random logical topologies with several connectivity degrees are
considered. The RWA problem under physical impairments has been solved versus D
and . The resource consumption is characterized by the average number n of
wavelengths used and the number nSL of Super-Lightpath routed. When a heuristic
optimizing the number of links occupied for each Super-Lightpath is used, we have
obtained for D==16 (n, nSL)=(24.3, 26) and (n, nSL)=(18.9, 145) when an S-RWA
problem with and without physical impairments is solved respectively. The increase in
number of Super-Lightpath was expected because the routing with physical
impairments leads to shorter Super-Lightpath so much more of them are needed to
solve S-RWA problem. On the contrary the lower number of wavelengths is explained
with a better distribution of the Super-Lightpaths on physical topology when physical
impairments are taken into account. In fact when they are not considered, Super-
Lightpaths are longer, it is more probable that two Super-Lightpaths have at least one
link in common and so a greater number of wavelengths are needed
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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